Ricoh G035 Service Manual page 478

DEVELOPMENT
Toner Supply Motor on Time Calculation
The toner supply motor on time is decided using the following formula:
2
0.7mg/cmx ImagePixelCount x Gain
.........................................................................................................(1)
Toner Supply Rate x K
(255 – Image Pixel Count) x Gain
.........................................................................................................(2)
255
⇒
NOTE: 1) The toner supply rate is fixed at 30.
2) K = Toner supply rate coefficient (fixed at 3.0).
3) The bracket (2) in the above formula is only used if Vtref < Vt.
4) The maximum toner supply motor on time is 1.2 s.
Vsp and Vsg Detection
The ID sensor (at the lower right area of the drum) detects the following voltages.
• Vsg: The ID sensor output when checking the drum surface.
• Vsp: The ID sensor output when checking the ID sensor pattern.
In this way, the reflectivity of both the drum surface and the pattern on the drum are
checked. This compensates for any variations in the reflectivity of the pattern on
the drum or the reflectivity of the drum surface.
The ID sensor pattern is made on the drum by the charge roller and laser diodes.
Vsg/Vsp is detected every 10 sheets printed to decide the new Vtref.
New Vtref Determination
Even if the toner concentration in the developer is maintained by checking the TD
sensor, the toner potential (chargeability) and the image density both change with
humidity and the amount of toner on the carrier. Therefore, the actual image
density, using the ID sensor output, is also used as one of the factors for deciding
the new Vtref, which is used for toner density control.
The new Vtref is determined using the following data.
• Vtref – Vt(10)
• Vsp/Vsg
From this point, toner density control is done using the new Vtref.
G035
+
6
2-30
Rev. 12/99
SM